Opposition

The lock-piece that turned a soft-prison strategy into an engine, and it did so by spending the one resource that nobody else was taxing: untapped creatures, not mana. Every creature you control is a tap, so the card scales with board width rather than with land count, and a stalled board for most decks becomes a runaway position for this one. The notorious build married it to creatures that make more creatures each turn, so the number of available taps outpaced anything the opponent could deploy: lands pinned before mana could be spent, threats tapped down on their controller's upkeep before they got a window to act, the loop tightening every turn the token count climbed. What makes the design durable is that the constraint is also the payoff. It does not destroy anything, and it does not freeze the untap step the way Winter Orb or Stasis do; it simply taps permanents back down before they matter, so they stay on the battlefield fully owned and fully useless. The strategic axis it exploits is the untap step itself: tap a permanent during its controller's upkeep and it sits idle through your entire turn, because it only untaps once a cycle. Permanents linger on the board, the controller assembles a position no single answer dismantles, and the gap between "I am locked out" and "I have already lost" narrows to nothing.